The present invention relates to an angular position indicator or display device, for remotely displaying the angular positions of element provided for assuming different angular positions and, in particular, valve elements, actuators and the like.
As is known, in several applications there occurs the need of displaying the angular positions of elements which can be turned through angles of 360.degree. or fractions thereof.
For example, in the case of ball or throttle valves, the displacement from an opening position to a closing position is usually performed through a rotation of 90.degree., and it is frequently necessary to clearly see from the outside the position assumed by the valve element.
At present for meeting the above mentioned requirements there are used very simple approaches, such as small arrows or indicating marks, which are applied, either directly or indirectly, to a projecting portion of a pin coupled to a rotary portion of the valve element, so that the arrow can indicate the assumed angular position.
Such an arrangement, which is actually very economic and simple, has however the drawback that the indication provided thereby can be seen only if it is observed perpendicularly to the axis of the reference arrow, whereas it is scarcely visible if the valve element is seen from a side.
For overcoming the above mentioned problem, there have been made indicating devices having a comparatively high vertical extension and practically comprising colored cylinders, including colored portions which turn rigid with the rotary axis of the valve or of the actuator therefor, within a clear casing, which bears correspondingly opaque portions allowing to selectively see the colored portion of the cylinder depending on the mutual positions thereof, so as to improve the lateral visibility characteristics.
On the other hand, such an embodiment allows only a partial vision, since the visible surface practically corresponds to a half of the side surface.
Another prior approach provides to divide the side surface of the cylindric body into a plurality of vertical rectangles bearing different colors on two faces thereof, said rectangles being caused to rotate by gear means adapted to rotate said rectangles through 180.degree. for each rotation through 90.degree. of the valve.
Thus, with the valve in an open condition, it is possible to see one face whereas, with the valve in a closed condition, it is possible to see the other face.
This arrangement, in addition to being very complex because of the gear means which must be used, has the further disadvantage that it does not allow to satisfactorily see the intermediate positions assumed by the valve element, since in these positions the rectangles are practically arranged on an edge thereof, thereby the angular position of the valve element can not be easily distinguished.